The present invention is in the general area of microelectrochemical devices and particularly relates to devices based on inorganic redox active material.
U.S. Pat. No. 4,721,601 discloses several types of novel microelectrochemical devices analogous to diodes, transistors, sensors, surface energy storage elements and light emitting devices which are formed from microelectrodes overlaid with electrochemically polymerizable redox materials. The physical properties of these materials change in response to a chemical or electrical signal altering the concentration of ionic species in the polymer. Examples of the redox polymers include polypyrrole, polyaniline, polythiophene, and other materials that are conducting when oxidized and insulating when reduced. Crucial to the practical application of most of these devices is the close spacing between electrodes, on the order of less than two microns, since the response time and sensitivity of the device depend on the spacing between electrodes as well as on the polymer selection.
Despite the tremendous potential and variety of applications made possible by the devices disclosed in U.S. Pat. No. 4,721,601 there remains a need for devices made with materials which transmit signals under different conditions (for example, when the redox material is reduced, rather than oxidized), which are more stable at extremes of pH or other environmental conditions, and which are sensitive to specific chemical signals.
It is therefore an object of the present invention to provide novel microelectrochemical devices formed with inorganic redox materials.
it is a further object of the present invention to provide such microelectrochemical devices exhibiting a reproducible proportional change in current as a function of pH or other specific chemical input.
It is still another object of the present invention to provide microelectrochemical devices which are stable in very basic electrolyte solutions and at other environmental extremes.